Quick and uncomplicated renovation of damp cellars

Waschküche im Keller mit einer Waschmaschine und einem weißen Regal vor einer weißen Wand. Davor sitz ein Beagel neben einem weißen Bast-Wächekorb und vor der Waschmaschine steht noch ein weiterer Wäschekorb mit Wäsche.

Dark, musty and damp – many basement rooms are anything but homely. Bicycles, tools or drinks can usually be stored there, but more is most often not possible due of the climate of such rooms. Damp cellars can also quickly become a problem for the building structure and must therefore be renovated by all means. Find out here what is important for renovation.

1. When should a cellar be renovated?

A cellar should be renovated at the latest whenever it is humid. Quick action is advisable so that the moisture does not spread further in the house and endanger the building structure. Nose and eyes provide the first information about damp walls and floors. If a cellar smells mouldly or musty, this is an indication. Other signs are for example flaking render, salt efflorescence or mould. This is particularly common in older cellars. With a professional renovation, the building structure and thus the house value can be maintained. Another benefit: after renovation, the rooms can be used better. If you hesitate, you should consult a skilled craftsman and, if necessary, have a professional diagnosis be carried out.

Professional tip

The dampness of a wall is roughly assessed by visual inspection or tactile testing in the following gradation: wet, damp, dry on the surface. For professional moisture measurements, drill cores are usually taken and analyzed in the laboratory. A simple alternative to drilling is the measurement with a hygrometer or moisture meter devices. The relative air humidity in the room and the humidity on the wall surface already provide information about possible moisture content. The measuring head of the hygrometer is placed on the wall at several points. Care should be taken with salt efflorescence, because it can significantly falsify measured values.

2. Which are the benefits of dry and habitable cellar rooms?

A refurbished cellar can be used in many ways. There is room for everything from clothes to electrical and sports equipment to furniture. A renovated basement is also often suitable as additional living space for sports, hobbies or parties. In addition to the living space, the rooms in the basement are suitable as work or guest room. A renovated basement increases the value of the real estate so that higher prices can be achieved when selling or renting it out.

3. What are the most frequent renovation works in basements?

Cellars are most frequently renovated because of moisture and salt contamination. These occur frequently in old buildings. This sometimes has to do with the construction method. In the past, cellars were mainly used for storing supplies. Here, there is often a lack of full-surface, all round waterproofing coating or horizontal moisture barriers against capillary rising damp. Also, defective external waterproofing coatings are the reason for the moisture and salt-contamination. Floods, defective water pipes and insufficient ventilation can be further causes of dampness in the cellar. Building components that are directly affected by moisture are usually the cellar walls and the floor.

4. How to renovate a basement space?

There are various methods to renovate basement walls and basement floors. This work should be carried out by professionals. Professional contractors for building protection and waterproofing specialists are the number one contact. They first check the condition of the masonry and determine the cause of the damage, as well as the moisture and salt load with special equipment. Then a so-called renovation concept should be drawn up, taking into account future use.

Cellars are often waterproofed from the internal side, if a retrospective external waterproofing of the earth-contacting walls fails, e.g. due to overbuilding.
The following measures have proven to be effective for simple and quick basement internal renovation:

Post-applied horizontal waterproofing

The purpose of a so-called horizontal waterproofing barrier is to stop the capillary rising damp into the walls and to protect the walls above the barrier. Horizontal waterproofing (or also cross-sectional waterproofing) can be post-applied without any problem. In this case, holes are drilled into the walls in a specific interval and filled with a silane-based injection cream.

Damp-proof render for the interior wall

In addition, a damp-proof render is applied on the prepared wall and after full removal of old render. Furthermore, the masonry joints must be scraped to a depth of approx. 2 cm prior to application. Damp-proof renders are particularly open to diffusion of water vapour and are able to absorb crystallizing salts due to their large air pores. In this way, they support the wall structure during drying. Complementary measures, such as drying devices, strong intermittent ventilation, etc. make sense, depending on the specific situation. Modern damp-proof renders can be applied in a single layer onto the pre-wetted masonry surface without any need for a separate spray bondcoat. They do not need to be painted over. In this way, cellar rooms can be renovated within one day.

Self-levelling and quick-setting smoothing mortar for basement floor

If the basement floor is drenched, a full-surface waterproofing layer must be installed as protection against rising damp after substrate preparation and priming. This can be done particularly quickly with a self-levelling and watertight floor compound, which both levels and waterproofs the floor in a thin layer. Once the material has hardened, the floor can be used directly as a wear layer without further over-working.

5. How long do renovation works take?

With well-implemented systems, the renovation of basement walls or floors can be done within one day. The skilled tradesman saves several work steps and thus also additional trips to the job site. In the best case, the measures are combined and, after the application of the renovation render, the basement floor is also waterproofed. The cellar room can be used again after only a short time.

6. Conclusion: a damp cellar is not to be joked about

Homeowners and residents should by no means come to terms with a damp basement. Damp basement walls and floors can cause considerable damage to the structure of the building. In addition, mould can also be harmful to health. Professional remediation is less costly than many people think. Depending on the damage and the area size, specialists can carry out a renovation with the reliable Saint-Gobain Weber interior basement repair system in one day. This keeps the property value and offers additional usable space that can be enjoyed for a long time.

Professional tip

The steps to be taken in the renovation process depend on the damage and the subsequent use of the basement. Skilled craftsmen can refer to the WTA leaflet 4-6 "Subsequent Waterproofing of Ground-contacting Structures" (WTA = International Association for Science and Technology of Building Maintenance and Monuments Preservation). It describes how various options for subsequent structural waterproofing and repair methods can be combined. Here, we have summarized the correct procedure for the repair of flood damages.